Respiratory assister



Allg 23, 1966 c. B. ANDREASEN ETAL 3,267,935

RESPIRATORY ASSISTER 5 Sheets-Sheet l Filed May 4, 1961 CHR|STIAPBNIFANI3QSSEN HAROLD K. RICHTER BYceoRcE H. sroNER MAM ATTORN EY 1lg 23, 1966 c. B. ANDREASEN ETAL 3,257,935

RESPIRATORY SSISTER Filed May 4, 1961 5 Sheets-Sheet 2 W* ATTORNEYS ug- 23, 1966 c. a. ANDREASEN ETA. 3,267,935

RESPIRATORY ASSISTER 5 Sheets-Sheet 3 Filed May 4, 1961 ATTORN EYS WW NRT Aug. 23, 1966 C. B. ANDREASEN ETAL 3,267,935

RESPIRATORY ASSISTER Filed May 4, 1961 5 Sheets-Sheet 4 ATTORNEYS Aug 23, 1966 c. B. ANDREASEN ETAL 3,267,935

RESPIRATORY ASSISTER Filed May 4, 1961 5 Sheets-Sheet 5 DURING INSPI RATION @gli END oF |N$P|RAT|0N- START oF EXPIRATION DURING EXPIRATION T S CHRISTIAN .YTIDCAS EN United States Patent O 3,267,935 RESPIRATORY ASSISTER Christian B. Andreasen, New Hope, Harold K. Richter,

Willow Grove, and George H. Stoner, Warminster, Pa.,

assignors to Air-Shield, Inc., Hatboro, Pa., a corporation of Delaware Filed May 4, 1961, Ser. No. 107,756 9 Claims. (Cl. 128-29) This invention relates to a device Afor assisting respiration, more particularly, to an intermittent positive pressure breathing device.

By an intermittent positive pressure breathing device is meant, a respiratory assister which delivers air under pressure to a patient (through a suitable mask or mouthpiece) during inspiration and also, preferably, provides for expiration against a positive pressure. The maintenance of positive pressure during exhalation is of assistance in maintaining the airways to the alveoli in open condition so that effective ventilation can take place.

Clinical studies have demonstrated the value of intermittent positive pressure breathing in the treatment and pulmonary rehabilitation of patients with respiration distress such as dyspnea, hard racking cough and tenacious sputum. Included in the conditions Which can be improved by the use of the intermittent positive pressure breathing apparatus of the invention are, chronic pulmonary emphysema, chronic bronchitis, pulmonary fibrosis, bronchial asthma, bronchiectasis, pulmonary edema, pneumoconiosis, cor pulmonale, bronchitis fibrosa obliterans, and pulmonary arteriosclerosis.

The beneficial results obtained by intermittent positive pressure breathing include the following:

(1) Ventilation is substantially improved without increase in the Work of breathing; the minute volume, vital capacity and maximum breathing capacity are increased and the residual volume is decreased.

(2) The alveoli are more uniformly and effectively ventilated, thus improving the gaseous interchange and raising the oxygen content of the blood.

(3) Improved alveolar ventilation also aids in the elimination of carbon dioxide, which is of special value because of the tendency f patients suffering from respiratory insuiciency to develop a respiratory acidosis. Improved elimination of carbon dioxide helps to restore sub-normal sensitivity of the respiratory center and aids pulmonary circulatory compensation.

(4) Oxygen or oxygen and helium mixtures can conveniently and efficiently be administered.

(5) Bronchial drainage can be encouraged by utilizing a peak expiratory flow rate greater than the peak inspiratory flow rate.

(6) A more efficient cough reflex is established.

(7) An effective dissemination of aerosols is provided, which aids in the medication of the bronchial mucous membranes, and this reduces bronchial resistance by relieving congestion of the membranes, loosening mucous plugs and reducing bronchospasm.

(8) An effective form of deep breathing exercise is performed, which helps to maintain tone in the muscles of respiration.

The above beneficial eiects of treatment with the intermittent positive pressure breathing apparatus of the invention cause marked symptomatic improvement in many patients. Breathing becomes easier, the exercise tolerance is increased, coughing and wheezing are reduced, appetite improves, expectoration is easier, and respiratory infections are less frequent and less severe.

Prior intermittent positive pressure breathing devices have been generally deficient in subtlety of control and sensitivity to patient breathing initiative, and have em- 3,267,935 Patented August 23, 1966 ice ployed relatively large and complicated apparatus depending for its operation upon an assured source of pressure gas, such as an air compressor, a tank of oxygen, etc. Such prior devices have thus not been readily available on a practical basis to most patients. Indeed, positive pressure breathing has normally only been able to be done in a physicians office, a clinic or a hospital.

The invention provides a respiratory assister, useful in the rehabilitation of patients suffering from chronic respiratory insufficiency, the assister being in the form of a compact and pneumatical-ly self-contained unit which is easily and conveniently portable and can be readied for operation at any location by simply plugging in an ordinary electric cord. The invention provides for the supply of a stream of air (with or without aerosolized medication and/ or humidification) under controlled pressure during inspiration, for a predetermined maximum inspiratory pressure, and for cycling at the will of the patient and in response to even slight inspiratory effort on the part of the patient. The invention provides separate and safe controls over inspiratory flow, maximum inspiratory pressure, and expiratory flow.

The primary object of the present invention is the provision of a portable and pneumatically self-contained positive pressure breathing device having a sensitivity to patient breathing initiative and a subtlety of cont-rol not heretofore available. It is, thus, contemplated that the invention be easily transportable by the patient to his home, or ofiice, or on trips, etc. so that the benefits of positive pressure breathing are readily accessible.

A further object of the invention is the provision of positive pressure breathing apparatus integrally incorporating means for -aerosolized medication and/ or humidication.

Still further the invention has as an object the provision of a positive pressure breathing device which delivers only thoroughly filtered air to a patient.

How the foregoing and other objects and advantages of the invention are attained will be seen from the following description taken with the accompanying drawings in Which:

FIGURE 1 is a sectional elevational view taken on the line 1, 1 of FIGURE 2 but with the gauge and solenoid valve shown in elevation;

FIGURE 2 is a plan section taken on the line 2, 2 of FIGURE 1 but with the motor housing appearing in full plan view;

FIGURE 3 is a vertical cross-sectional view taken on the line 3, 3 of FIGURE 1 with the leaf spring assembly and the diaphragm structure appearing in full elevation;

FIGURE 4 is a fragmentary cross-sectional view taken on the line 4, 4 of FIGURE 2;

FIGURE 5 is a perspective view of the invention, on a reduced scale;

FIGURE 6 is an enlarged sectional view of the exhaust valve associated with the patients mouthpiece;

FIGURES 7 and 8 are wiring diagrams showing two embodiments of the invention; and

FIGURES 9 through 13 `are diagrammatic views showing the conditions of parts of the `apparatus during the different phases of the operation thereof.

The various parts of the invention are preliminarilyv protrudes downwardly through the fan housing 15. On the motor shaft 25, the fan, including discs 26 and 27, is mounted for rotation. The discs 26 and 27 carry fan blades 28 and 29, respectively. During rotation of the fan, air is sucked into the bottom of the fan housing 15 through the aperture 30. It is here noted that the casing 16 includes appropriate rubber legs 31 which may rest on the floor or a table and which hold the bottom surface 32 of the casing 16 out of contact with the supporting surface. The crack beneath the casing 16 provides for the ingress of air into the bottom of the unit, from which the air passes upwardly through the foraminous cover plate 33 and through the aperture 30, as above described.

Under the action of the fan blades 28 and 29, a positive pressure is 'built up within the fan housing 15 and air under pressure is delivered (see FIGURE 2) through the air flow conduit means 34 to the main air valve 17.

The main air valve 17 includes a valve housing 35 and a solenoid 36 associated therewith and adapted to open and close the main valve upon energization and deenergization, as described more fully below.

From the main valve 17 the stream of air under pressure flows through the conduit 37 of the inspiratory flow control device 42 (described below) and into the check valve chamber 38 (see FIGURES 2 and 4). The check valve chamber 38 includes a valve disc 39 adapted to seat against the valve seat 40, the disc 39 being held within the disc cage 41. The check valve 39 is oriented lso as to permit flow in direction from the fan toward the patient and to prevent flow in the opposite direction.

The inspiratory flow control block 42 is provided with a bore 43 within which the rotatable cylinder 44 is mounted. VThe cylinder 44 has intersecting bores 45 and 46 providing a flow passage through the cylinder. When the cylinder 44 is in the angular position illustrated in FIG- URE 4, the bore 45 is aligned with the corresponding bore 47 in the block 42 into which the end 48 of the pipe 37 (FIGURE 2) is screwed. The bore 46 is, in this position, aligned with bore 49 in block 42 which is, in turn, aligned with bore S in the lower valve housing 51.

From the enlarged flange 52 on the cylinder 44, the stop pins 53 and 54 protrude in radial direction at 90 to each other. A cooperating abutment pin 55 is provided protruding from the block 42 in position to abut the pin 54 in the extreme angular position of the cylinder 44 which is illustrated in FIGURE 4, and to abut the pin 53 when the cylinder 44 is rotated 90 in a counterclockwise direction. When the cylinder 44 is rotated so that the pin 53 abuts the pin 55, the flow passage through the cylinder 44 will be occluded because the end of the bore 45 will be disposed toward the wall of the bore 43 instead of toward the bore 47.

From the foregoing it will be seen that angularly positioning the cylinder 44 intermediate the extreme positions provides for a greater or lesser interference with the flow of air through the bores 4S and 46. By this means a sensitive control of inspiratory ow is attained.

The Iangular position of the cylinder 44 is determi-ned by the control knob 56 (FIGURE 2) secured by a set screw 57 to the flexible shaft 58 passing through the wall of the casing 16, through the flexible cable 59 and into an aperture in the end of the cylinder 44, in which aperture the flexible shaft 58 is secured by means of the set screw 60. The flexible shaft 58 provides a direct mechanical interconnection between the rotatable knob 56 and the rotatable cylinder 44.

From the check valve chamber 38 the stream of air under pressure flows through the apertures 61 in the retaining ring 62 into the upper portion 63 of the filter chamber 1S. A pad of filter medium 64, such as glass fibers, separates the upper portion 63 from the lower lter chamber portion 65' so that the entire air stream must pass downwardly through the lter material 64. The edge of the pad 64 is squeezed, as shown at 66, be-

tween the retaining ring 62 and the shoulder 67 of the lower chamber 65.

'Ille retaining ring 62 depends from a removable cover plate 68 having a large aperture 69 therethrough. The aperture 69 is covered by a sight glass 70 so that the operator can readily observe the relative cleanliness of the filter pad 64 by looking downwardly through the aperture 69 and the sight glass 70.

From the lower filter chamber 65 the stream of filtered air flows through the channels 71 and 72 into the aerosol chamber 19.

The aerosol chamber 19 is formed 'by a generally cylindrical upper side wall 73, an inwardly sloping bottom wall 74, reservoir walls 75, and bottom wall 76. The reservoir wall 75 and bottom wall 76 form a cup-shaped extension below the central portion of the aerosol chamber 19 and provide for a reservoir of water and/or liquid medication, indicated at 77.

The top cover 68 extends over the aerosol chamber 19 and, above the aerosol chamber, includes an aperture 78 provided with a sight glass 79 so that the operator can observe the functioning of the aerosol device by looking downwardly through the aperture 78 in the sight glass 79. A fill orifice 80 is provided in the cover plate 68 and, when not in use, is plugged by a threaded plug 81.

A series of radial fins 82 protrude upwardly from the sloping wall 74 and support the disc housing 83 having a horizontal flange 84 slotted as at 85 (FIGURE 2) to accommodate the ns 82 and position the disc housing 83.

Within the disc housing 83 there is provided a thin circular disc 86 keyed, as by key member 87, to disc shaft 88 journalled in upper bearing 89 and lower bearing 90. The upper bearing 89 and lower bearing 90 are carried in hollow bearing shaft 91 which is supported in spaced rubber grommets 92 and 93 which are, in turn, supported by the cylindrical standard '94 and bottom cap 9S. lt is to be understood that the shaft 88 rotates and that the bearings 89 and 90, and the shaft 91 are fixed against rotation.

A tapered sleeve member 96 extends downwardly from a collar 97 depending from the underside of disc 86. Apertures 98 pass through the collar 97 and communicate with the interior of the sleeve 96. When the disc is rotated, water ows up the tapered sleeve 96, through the apertures 98 and onto the upper surface of the disc 86. The water rapidly spreads into a thin lm on the upper surface of the disc 86 and is hurled outwardly by centritug-al force. The water lilm breaks into small particles which leave the disc tangentially at high velocity and strike the serrations 99 around the inside of ring 100. Upon striking the serrations 99 the particles of water split into minute particles most of which are small enough to be suspended in the air. The larger particles are removed frorn the air prior to the delivery thereof to the patient by striking the top plate or walls of the aerosol chamber 19. To assist in the removal of larger particles, the shroud 101 extends substantially half way around the ring 100 and protrudes upwardly therefrom in position to prevent the air stream from ilowing relatively directly through the aerosol chamber 19 and out of the exit passage 102. Relatively direct flow through the chamber 19 might result in the entrainment of liquid particles of larger than desired size. The shroud 101 prevents particles of larger than desired size from being hurled directly out of the exit passage 102 by the whirling disc, because the tangential paths from the disc directly to the eXit passage 102 are blocked by the shroud 101.

The disc 86 and disc shaft 88 are rotated by means of the pulley 103 mounted on the lower end of the shaft S8, the belt 104, and the pulley 105 mounted on the lower end of the motor shaft 25.

Radial vanes 106 protrude downwardly from the disc housing member 83 and minimize rotation of the body of water in the reservoir. Rotation of the water would tend to result in the centrifugal distribution of the water in a' cup or whirlpool and this would interfere with water ow up through the tapered sleeve 96.

The grommet 92 provides an effective water seal to prevent the water in the reservoir from leaking out around the bearings.

The filtered and aerosolized stream of air under pressure is delivered from the aerosol chamber 19 through the exit opening 102 and the exit connector 107 which is adapted to be connected with a length of flexible plastic or rubber tubing 108 preferably incorporating a helical reinforcing wire 109. The delivery tubing 108 (see FIGURE 6) leads to the connector fitting 110 of the patients mouthpiece device 21.

As best seen in FIGURES 2 and 6, a small yconduit 111 is branched from the conduit 37 by means of a T connector 112. The small conduit 111 extends out of the unit inside of the tubing 108 and the outer end 113 thereof lits into the passage 114 provided through the wall 115 of the mouthpiece assembly.

The mouthpiece 116 is tapered as at 117 to provide a friction tit with the tapered aperture 118 in the mouthpiece device 21. A bore 119 extends through the mouthpiece device 21 and thus interconnects the hose 108 and the bore 120 of the mouthpiece 116.

An exhaust valve generally indicated at 121 is provided on the mouthpiece device 21. The exhaust valve 121 includes a valve chamber divided by means of the liexible diaphragm 122 into a rst, or lower, compartment 123 and a second, or upper, compartment 124. The diaphragm 122 carries, centrally, discs 125 and 126 mounted in aligned position against opposite faces there- 0f. The lower disc 125 serves as a valve member and, for this purpose, is adapted to seat against the O ring 127 retained in position by means of the shoulder 128. The bore 129 provides for the exposure of the compartment 123 to the pressure within the bore 119 of the mouthpiece device 21 and thus to exposure to the pressure within the patients lungs.

The diaphragm 122 and discs 125 and 126 are biased toward the downward position by means of a compression spring 130 which abuts the upper surface of the disc 126 and the roof 131 of the upper chamber 124. The spring is retained in position by means of the shoulder 132.

An exhaust vent 133 vents the lower chamber 123 to atmosphere. When the disc 125 is in the downward position against the seat 127, the iiow of air from inside of the mouthpiece device 21 (and thus from inside the patients lungs) into the compartment 123 is prevented. However, when the disc 125 is cracked off of the seat 127, air can exhaust from the patient through the bore 129 and the chamber 123 and out through the exhaust vent 133. The exhaustion of air through the vent 133 takes place when the pressure differential across the diaphragm 122 is such as to result in the upward displacement of the diaphragm from the position shown in FIG- URE 6.

Abutment means 1 34 in the form of an enlargement at the end of a threaded member 135 is positioned to limit the upward travel of the disc 126. By rotating the control knob 136 the relative position of the threaded member 135 within the collar 137 is adjusted to Iprovide for the extension of the abutment means 134 downwardly to a greater or lesser degree. The knob 136, threaded member 135 and abutment means 134 will remain in the adjusted position because of the frictional retarding force developed by the O ring 138 which engages the abutment means 134 and the wall of the surrounding shoulder 132.

By adjusting the position of the abutment means 134, the degree of possible displacement of the diaphragm and disc assembly off of the seat 127 is controlled, and provides for a greater or lesser interference with the outiiow of air from the patient through the exhaust vent 133. The control knob 136 and associated parts thus provide a sensitive expiratory ow control.

The passage 114 interconnects with a similar passage in the cap 131 of the exhaust valve 121. The diaphragm 122 is clamped around its periphery between the flange 151 on the cap 131 and the flange 152 on the body of the Valve structure. The diaphragm is apertured to provide communication between the passage 114 and the passage 150. The passage 150 opens into the upper chamber 124. The small conduit 111 and the passages 114 and 150 thus provide for the exposure of the compartment 124 and the upper side of the diaphragm to the pressure in the air flow line 37 between the main valve 17 and the inspiratory ow control block 42.

As best seen in FIGURE 9, the main air valve 1'7 includes a solenoid follower 153 which carries a valve disk 154 adapted to seat, in the upper position, against the seat 155 and thereby occlude flow from the fan through the conduit 34. In the upward position in which flow from the fan is occluded, the vent 156 is uncovered and communicates with the open end of t-he conduit 37. The conduit 37, from the check valve disc 39 to the main air valve 17, is thus vented to atmosphere when the rnain air valve is in the closed position.

Since the sma-ll pressure 'line 111 connects into the line 37, the line 111 and thus the upper compartment in the exhaust valve 121, will be vented to atmosphere when the main air valve is in the closed position. This arrangement relieves the pressure on the upper side of the exhaust valve diaphragm 122. Pressure from the patents lungs during the start of the expiration phase will lift the diaphragm 122 and the disc 125 off the seat 127 and penmit the expired air to exhaust through the vent 133.

However, as soon as lthe main air valve is opened by the operation of the solenoid, pressure air tiows through the small line 111 land lls the upper compartment in the exhaust valve and thereby assists in seating the disc 125 on the seat 127 and thus occluding the exhaust vent 133.

When the main air valve is in the open position, see FIGURE 10, the vent 156 is closed by the bottom surface of the solenoid follower 153.

Attention is now turned to a particularly important part of the invention. As seen in FIGURE l, the diaphragm structure 22 includes an upper housing 157, an intermediate housing 158, and a lower housing 159 which are assembled together and supported by the channel niember 160. A first or lower diaphragm 161 and a second or upper diaphragm 162 are arranged in spaced relation within the diaphragm structure with the peripheries of the diaphragms held rmly between the members 157- 159. The diaphragms 161 and 162 thus divide the interior of the diaphragm structure 22 into an upper space 163, an intermediate space 164, and a lower space 165.

The diaphragm 161 carries central discs 166 and 167 on the lower and upper faces thereof and also follower pin 168 depending therefrom. Upward diaphragm 162 has similar discs 169 and 170 against the lower and upper 'faces thereof and an upstanding Vfollower pin 171.

The follower pin 168 of lower diaphragm 161 is adapted to actuate the mirco switch 172 which is electrically interconnected with the solenoid 36 of the main air valve.

y The follower pin 171 of the upper diaphragm 162 irnpinges on the spring nger 173 which, in turn, actuates the micro switch 174 also electrically connected with the solenoid 36.

A spring finger 173 is secured by screws 175 to block 176 mounted for rotation about the pin 177 secured to the channel member 160. The upper end of block 176 is in contact with the threaded pin 178, to the other end of which the control knob 179 is atiixed. Rotation of the control knob 179, by means of the threads on the pin 178, adjusts the force exerted against the upper end of the block 176 and, since block 176 is pivoted at 177, this results in the application of a greater or lesser yielding force against the pin 171 via the spring finger 173.

The spring iin-ger 173 and associated control structure thus provided a direct and accurate control of the force applied to the upper diaphragm 162 in direction urging said diaphragm away from the micro switch 174.

The space 164 (FIGURE l) between the diaphragms 161 and 162 is exposed to the pressure in the chamber 65 below the filter member 64 by means of the conduit 186 (FIGURE 3) and the associated connectors 181 and 182.

Relay means 183 may conveniently be mounted on the channel member 166 and function in a manner described more fully below.

The motor and fan housings 14 and 15 are secured to the top 134 of the casing by means of the downwardly projecting standards 185, the bolts 186, the rubber vibration absorbers 187 and the washers 188.

The pressure gauge 23 housed in housing 139 is secured to the underside of the top 184 by screws 199 and is aligned with an aperture 191 through the top which is covered with sight glass 192. The pressure gauge, by means of the conduit 193 interconnecting wit-h the T member 194, is exposed to the pressure within the lower lter chamber 65 and thus gives la visual indication of the pressure to which the patient is exposed.

Attention is now turned to the wiring diagrams of FIGURES 7 and 8. rhe motor 24 is connected to line voltage through the main switch 195 controlled by the toggle 196 (FEGURE 5).

In the embodiment of FIGURE 7, the relay 183 is comprised of a coil 19S which is connected to the power source 263-294 through switch 197 shown in open condition and switch 199 shown in closed condition. The coil 198 actuates the ganged switches 291) and 261. Gne side of the solenoid 36 is connected with one side 2.03 of the line by means of the lead 2il3a. The other side of the solenoid 36 is connected, through lead 20S, switch 291 and lead 266 with the other side 264 of the line. The coil 198 is connected to the side 2114 of the line by means of the lead 266, the lead 207, the switch 260, and the lead 298 which is connected at 299 between the switches 197 and 199. The other side of the relay is connected to the side 263 of the line.

The embodiment Vof FIGURE 7 operates as follows. The operator rst closes the switch 195 by means of the toggle 196. With the mouthpiece 21 in the patients mouth, the initial inspiratory effort of the patient causes a drop in pressure within the chamber 164 between the control diaphragms 161 and 162. The lower diaphragm 161 flexes upwardly in response to the drop in pressure. The upper diaphragm 162 remains in the downward position because of the urging of the spring inger 173. Upon the upward flexing ofthe diaphragm 161, the micro switch 172 is :actuated to close switch 197 (FIGURE 7). Upon closing of the switch 197, the relay 198 is energized and closes the switches 200 and 201. Thereafter, continued energization of the relay 198 and the solenoid 36 are independent of the condition of switch 197, since the relay 198 holds the switches 200 and 281 in closed condition and switch 197 is bypassed by the lead 206. Eventually the pressure in the chamber 164 between the diaphragms 161 and 162 builds up to a point where the upper diaphragm is flexed upwardly to a position in which the micro switch 174 is actuated to open the switch 199. As soon as the switch 199 is opened, the relay 198 is deenergized, the switches 200 and 201 return to open condition, and the solenoid 36 is deenergized.

FIGURE 8 illustrates another electrical circuit according to the invention. The latching relay 210 includes a latching coil 211 and a release coil 212. The latching coil 211 is adapted, upon energization, to close the switch 213. Upon closing of the switch 213, the l-atch 214 is moved, by means of the spring 215, into a position in which it holds the switch 213 in closed condition. Energization of the rele-ase coil 212 removes the latch 214 from the path of switch 213 and permits the switch to open under the action ofthe spring 216.

One side of the latching coil 211 is connected by lead 217 with one side 203 of the line. The other side of the coil 211 is connected by the lead 218 to the other side 204 of the line through the switch 219. The switch 219 assumes the closed condition upon actuation of the micro switch 172 by downward exing of the lower diaphragm 161. When the switch 219 is closed, and thus the switch 213 is closed, the solenoid 36 is connected across the line by means of lead 229, switch 213, lead 221, and lead 222. The solenoid will continue to be energized, independent of; the condition of the switch 219, because of the action of the latch 21d which holds the switch 213 in closed condition even if the latching coil 211 is deenergized.

The buildup of pressure between the diaphragms eventually ilexes the upper diaphragm 162 to the point where the micro switch 174 is actuated to close the switch 223 and energize release coil 212. At this point the latch 214 is moved out of the way of the switch 213 and the switch 213 opens and deenergizes the solenoid 202.

Attention is now turned to the diagrammatic views in FIGURES 9-13 which illustrate the diiierent conditions of the equipment during operation. As indicated on these figures, FIGURE 9 illustrates the condition during the pause after expiration has ended and before inspiration begins, FIGURE l0 illustrates the condition at the very beginning of the next inspiration, FIGURE l1 illustrates the condition during inspiration and before the full maximum positive pressure has been developed in the patients lungs, FIGURE 12 illustrates the condition at the end of inspiration and the start of expiration, that is, the point of attainment of the maximum predetermined pressure in the patients lungs, and FIGURE 13 illustrates the condition of the equipment during expiration.

Initially, it is mentioned that the device can be readily carried by the handle 224 (FIGURE 5) to any location convenient for the patient. The condition of the filter member 64 can be observed through the sight glass 70 and, in the event that the lter appears to be dirty and requires changing, the cover plate 68 can be released from the catches 225 (one of which appears in FIGURE 5). Removal of the cover raises the ring 62 and a clean filter pad 64 can be inserted. Replacement of cover 68 brings the ring 62 into engagement with the edges of the lter pad and holds the pad in proper position.

The plug S1 may be unscrewed to expose the till opening and water and/or liquid medication can be poured into the aerosol chamber 19.

If it is desired to supplement the air flowing to the patient with oxygen and/ or helium, this can convenietly be done by removing the plug 226 (FIGURE 2) and attaching a source of the desired supplementary gas to the nipple 227 which communicates with the interior of the aerosol chamber 19. When not in use, the plug 226 is retained against loss by means of chain 228.

When the lter is clean and in position, appropriate liquid is in the reservoir, and, if desired, a source of oxygen or other supplementary gas is connected to the aerosol chamber, the unit is plugged into an ordinary source of house voltage by a conventional cord and plug (not show). The unit is turned on by means of the toggle switch 196 and the mouthpiece device 21 is gripped in the patients mouth. The motor is now in operation and rotates the fan and aerosol disc so that pressure air and aerosolized liquid are developed. Proper functioning of the aerosol device can be observed through the sight glass 79, that is, it can be observed whether or not the disc 86 is revolving and whether or not fog or mist is being generated in the aerosol chamber 19.

In FIGURE 9, the main air valve 17 is in closed condition so that t-he conduit 34 is occluded. In this condition the conduit 37 is vented to atmosphere through vent 156. The upper compartment 124 of the exhaust valve 121 is also vented to atmosphere via the small pipe 111, conduit 37, and vent 156. The diaphragm 122 is yieldingly held in the downward position by the spring (and also by the force of gravity). Since the diaphragm 122 is in the downward position, the exhaust vent 133 is occluded. The diaphragms 161 and 162 are in the downward positions, the diaphragm 161 being urged toward the downward position by the force of gravity 4and the diaphragm 162 being yieldingly held in the downward position by the spring linger 173. The switch 172 is open and the switch 174 is closed. The check valve 39 is in iclosed condition.

Attention is now direc-ted to FIGURE 10. As the patient begins to inhale, a slight negative pressure is developed in the patients lungs by reason of the mechanical expansion thereof by the chest muscles. The slight negative pressure in the patients lungs is applied to the chamber 164 between the diaphragm 161 and 162, and causes the lower diaphragm 161 to flex upwardly, as shown in FIGURE l0, and permits the switch 172 to close. The diaphragm 162 remains in the downward position.

The closing of the switch 172 effects energization of the solenoid 36 so t-hat the main air valve 17 opens and permits pressure air to flow from t-he conduit 34 into the conduit 37. At the same time, the vent 156 is closed. Pressure air is delivered from the conduit 37, via the small conduit 111, to the upper side of the diaphragm 122, and aids in holding the diaphragm in the downward position. Pressure air is also delivered through the bore 49 and lifts the check valve 39 off of its seat 40 so that the pressure air flows in above the filter, down through the filter, and into the Vaerosol chamber 19. From the aerosol chamber 19 the filtered and aerosolized air fiows through the flexible hose 20 and into the patient through the mouthpiece 21.

Attention is now turned to FIG. 11. At a point during inspiration shortly after that illustrated in FIG. 10, the parts assume the positions shown in FIG. 1l. rllhe pressure air has now developed a positive pressure in the chamber 164 between the diaphragms 161 and 162. The diaphragm 161 has been flexed to the downward condition and the switch 172 has reopened. No change in the energization of the solenoid 36 takes place because of the special electrical circuit employed, as above described. The diaphragm 162 was exed slightly upwardly but has not yet reached the point at which the switch 174 will open. During the condition of FIG. 11 pressure air is being fed into the patients lungs.

FIG. 12 shows the condition of the parts at the moment when the pressure built up in the patients lungs and' in the chamber 164 between the diap-hragms has reached the desired predetermined maximum level. At this point the downward urging of the spring finger 173 is overcome so that the switch 174 is opened and the solenoid 36 deenergized. The main air valve 17 thus returns to closed condition, as does the check valve 39.

It is here pointed out that the exhaust Valve 121 remained closed during the entire inspiratory phase, including the condition shown in FIG. 11. Positive closing of the exhaust valve 121 is facilitated by the fact that the exhaust valve diaphragm 122 (FIG. 6) is exposed -to pressure differentially when in the downward position. Although the diaphragm 122 is exposed to the pressure air on both the upper and lower sides, the .area on the upper side exposed to the pressure is substantially greater than the area on the lower side exposed to the pressure, with the result that there is a net downward force.

In FIG. l2 the upper side of the exhaust valve 121 is vented to atmosphere through the conduit 111, the conduit 37 and the vent 156. Since the air within the patient and the rest of the .apparatus is still at a positive value, the diaphragm 122 of the exhaust valve will flex upwardly as shown in FIG. 12 and expose the vent 133. Since the check valve 39 is closed and there is no other way for the gas to flow, the gas within the patients lungs will ow outwardly through the exhaust vent 133 during expiration. This effects .an important safety feature of the invention, namely, contaminated air from the patients lungs cannot ow backwardly into the aerosol or filter chambers. As a result, the unit can be used for successive patients, after sterilization of the mouthpiece only, without fear of cross infection.

FIGURE 13 illustrates the parts during expiration. The exhaust valve 121 remainsiin open condition so that the air is exhausting from the patients lungs to atmosphere. The pressure in the chamber 164 has fallen to the point where the upper diaphragm 162 has begun to flex downwardly and the switch 174 has returned to closed condition. The lower diaphragm 161 is in the downward position. As soon as expiration is completed, the exhaust valve 121 will return to the closed position, because the combined force of gravity and the spring (FIG. 6) will then take over the function of positioning the diaphragm 122 in the absence of positive pressure against the bottom side of the diaphragm. The diaphragm 162 will also complete its return to the downward position. All of the parts are ready to recycle and the next inspiratory phase will be triggered by the initial inspiratory effort of the patient.

The physician will advise the patient of the desired maximum pressure to be used by the patient. Manipulation of the control knob 179 coupled with observation of the pressure developed, as indicated by the pressure gauge 23, will thereafter enable the patient to administer positive pressure breathing to himself in exactly the degree desired by his physician.

Furthermore, by relative manipulation of the inspiratory tiow control knob 56 and the expiratory flow control knob 136, the relative rates of inspiration and expiration can be adjusted. It is often desirable to adjust the inspiratory and expiratory rates so that the peak expiratory rate exceeds the peak inspiratory rate since this arrangement facilitates bronchial drainage.

Treatment is generally desirably administered for a period of about twenty minutes at a time. At the beginning of treatment by positive pressure breathing, it is usually desirable to administer the treatment several times a day, this frequency being continued for at least about three weeks, or as long as the patient continues to show improvement. Thereafter, maintenance of the improved condition of thev patient can usually be accomplished by less frequent administrations of positive pressure breathmg.

In general, a pressure of .about 20 cm. of water is desirable; patients with pulmonary fibrosis may need a higher pressure for a beneficial response, and those with a history of spontaneous pneumothorax are generally treated are generally treated with a lower pressure.

The emphysematous patient usually finds an early morning treatment particularly helpful in aiding elimination of retained secretions and promoting effective .alveolar aeration. The asthmatic patient may find bedtime treatment the most useful. Patients who have developed respiratory acidosis may need several full treatments a day for a considerable time to get rid of accumulating carbon dioxide.

Stated in brief, the invention provides, for the first time, a portable and pneumatically self-contained positive pressure breathing device with `a subtlety and yaccuracy of control not heretofore available. Furthermore, the invention provides for thorough filtration of the air delivered to the patient, and for aerosolized medication and humidification and for the utilization of supplementary oxygen as may be needed.

The inertia of the check valve 39, when in the closed position of FIG. 9, must be sufficient to insu-re that the valve remains closed at the start of inspiration during the short interval necessary to effect upward exure of 4the diaphragm 161. If the valve 39 opened instantly at the start of inspiration, air could ow in through the vent 156 and impair the proper functioning of the uni-t.

The control knobs 56, 179 and 136 can, if desired, be made readily removable so that the physician can preset the controls and then remove the knobs. Improper :ad-

iustment of the controls by the patient can thereby be avoided.

We claim:

1. A respiratory assister having a portable casing in which are housed the parts of a pneumatically self-contained assembly including fan means for generating a stream of air under pressure above atmospheric, `and motor means for driving the fan means, the assembly comprising a patients delivery device, conduit means for connecting the fan means with the patients delivery device, a main control valve disposed in the conduit means, an exhaust port for connecting the conduit means to atmosphere iat a point between the main control valve and the patients delivery device, lan exhaust port valve responsive to expiration by the patient to open the exhaust port, a iiuid pressure device for urging the exhaust valve toward closed position during inspiration by the patient and including :a fluid pressure control line having a point of connection with the conduit means between the main valve and the exhaust port, -a check valve in the conduit means between said connection point and the exhaust port, said check valve being oriented to permit air flow in the direction from the fan toward the patients delivery device 'and to prevent air iiow in the opposite direction, control mechanism for the main control valve including a iirst diaphragm moveable to a control position in response to -a build-up of pressure in the conduit means between the check valve and the patients delivery device, a second diaphragm movable to a control position in response to a build-up of pressure in the conduit means between the check valve and the patients delivery device to close the main valve, la pneumatic connection between said diaphragms and the conduit means, means interconnecting said diaphragms and said main control valve for opening the main valve when the iirst diaphragm moves to its control position and for closing the main valve when the second diaphragm moves to its control position, a port for venting the iiuid pressure control line; and means associated with the main valve to open the port upon closure of the main valve and to close the port upon opening of the main valve.

2. A construction according to claim 1 in which the control mechanism -for the main air valve comprises a solenoid, said iirst control diaphragm in the control position effects energization of the solenoid, the solenoid being connected in an electric circuit such that, :after initial energization of the solenoid, continued energization of the solenoid is independent of the position of said rst control diaphragm, the construction further including means for terminating the energization of the solenoid, said second control diaphragm, upon reaching a control position, being effective to actuate said means and deenergize the solenoid.

3. A construction laccording to claim 2 in which the electric circuit includes a iirst switch operable by said first diaphragm and a relay controlled by said switch, said elements being arranged so that the assumption by the rst control diaphragm of the exed position closes said iirst switch and energizes said relay, said relay upon energization, causing energization of said solenoid, holding circuit means for maintaining said solenoid energized irrespective of energization of the relay, and a second switch, said second switch being in said holding circuit and controlled by said second diaphragm, the second diaphragm being operable to open said second switch to de-energize the relay upon movement of the diaphragm t-o control position.

4. A construction Vaccording to claim 2, further including a irst switch controlled by said rst diaphragm and a latching rel-ay having -a latching coil and a release coil, said latching coil being energized by said switch when the iirst diaphragm moves to control position, a second switch, said second switch being controlled by said second diaphragm and being connected to said release coil to energize said coil when the second diaphragm moves to l2 control position, said latching relay being connected to the solenoid to energize the solenoid when in the latched condition.

S. A construction according to claim 1 and further including yielding means urging the second control diaphragm away from a control position, and control means for adjusting the urging force Iapplied by said yielding means.

6. A construction according -to claim 1 in which the pair of flexible control diaphragms are held in space relation around the peripheries thereof, and in which the space between the control dia-phragms is exposed to the pressure in the patients delivery device.

7. A construction according to claim 6 further including adjustable spring means for yieldably urging the second of said control diaphragme away from the exed position, .and further including control means for adjusting the force applied to the diaphragm by said spring means.

S. A respiratory assister having a portable casing in which are housed the part-s of a pneumatically self-contained assembly including fan means for generating a stream of lair under pressure above atmospheric, and motor means for driving the fan means;

the assembly comprising a patients delivery device, conduit means for connecting the ian means with the patients delivery device, a main control valve disposed in the conduit means,

an exhaust port for connecting the conduit means to atmosphere at a point between the main control valve and the patients delivery device, an exhaust port valve responsive to expiration by the patient to open the exhaust port,

a fluid pressure device -tor urging the exhaust valve toward closed position during inspiration by the patient yand including a fluid pressure control line having a point of connection with the conduit means between the main valve and the exhaust Iport,

a check valve in the conduit means between said connection point and the exhaust port, said check valve being oriented to permit air flow in the direction from the fan toward the patients delivery device and to prevent air flow in the opposite direction,

control mechanism for the main control valve including pressure responsive means, responsive to a pressure drop in the conduit means between the check valve and the patients delivery device to open the main valve, said pressure responsive means being further responsive to a build-up of pressure in the conduit means between the check valve 'and the patients delivery device to close the main valve,

a port for venting the portion of the conduit means between the main valve and the check valve means connected with said main valve and controlled thereby to open the por-t to effect such venting upon closure of the main valve.

9. A respiratory Iassister comprising, as a port-able assembly, an air supply system including a fan and a motor therefor, a device for delivering air to a patient, and conduit means interconnecting the delivery side of said fan and the patient delivery device, main valve means interposed in the conduit means and .adapted to controllably assume a delivery condition in which iair is permitted to ow through the conduit means and a closed condition in which air flow through the conduit means from the fan is occluded, an aerosol device interposed in the conduit means between the main valve means and the patient delivery device, the aerosol device including means for gener-ating a suspension of liquid particles in the air flowing through the unit and into the patient, the conduit means having an exhaust port located between the aerosol device and the patient delivery device providing lfor patient expiration to a zone external of lthe air supply system, la check valve in said conduit between the main valve means and lthe exhaust port, said check valve being oriented to permit air dow in the direction 13 from the fan toward the patients delivery device and to prevent air ow in the opposite direction, an exhaust port valve responsive -to patient expiration to open the exhaust port, a fluid pressure device for urging the exhaust port valve Itoward closed position during inspiration by the patient and including a iluid pressure control line having a point of connection with the conduit means between the main valve means and the check valve, pressure responsive control mechanism, -a fluid pressure connection between the pressure responsive mechanism and the conduit means at a point between the check valve and the patient delivery device, said pressure responsive control mechanism being operable to assume a first control condition in response =to a drop in pressure in said conduit means and a second control condition in response to la build-up of pressure in the conduit means to effect the open condition by the main valve means when in said rst control condition and to effect the closed condition by the main valve means when in said second control condition, -a vent -for said pressure control line and means connected to said main valve means for opening the vent when the main valve means is closed and for closing the vent when said main valve means is opened.

References Cited by the Examiner UNITED STATES PATENTS 2,391,877 l/1946 Cahan 137-64 2,582,210 1/1952 Stanton 128-29 2,774,346 12/ 1956 Halliburton 128-29 2,834,339 5/ 1958 Bennett 128-29 2,969,789 1/ 1961 Morch 128-29 2,972,345 2/1961 Spigel 12S-29 3,028,873 4/1962 Kindred 128-188 RICHARD A. GAUDET, Primary Examiner. C. F. ROSENBAUM, Assistant Examiner. 

1. A RESPIRATORY ASSISTOR HAVING A PORTABLE CASING IN WHICH ARE HOUSED THE PARTS OF A PNEUMATICALLY SELF-CONTAINED ASSEMBLY INCLUDING FAN MEANS FOR GENERATING A STREAM OF AIR UNDER PRESSURE ABOVE ATMOSPHERIC, AND MOTOR MEANS FOR DRIVING THE FAN MEANS, THE ASSEMBLY COMPRISING A PATIENT''S DELIVERY DEVICE, CONDUIT MEANS FOR CONNECTING THE FAN MEANS WITH THE PATIENT''S DELIVERY DEVICE, A MAIN CONTROL VALVE DISPOSED IN THE CONDUIT MEANS, AN EXHAUST PORT FOR CONNECTING THE CONDUIT MEANS TO ATMOSPHERE AT A POINT BETWEEN THE MAIN CONTROL VALVE AND THE PATIENT''S DELIVERY DEVICE, AN EXHAUST PORT VALVE RESPONSIVE TO EXPIRATION BY THE PATIENT TO OPEN THE EXHAUST PORT, A FLUID PRESSURE DEVICE FOR URGING THE EXHAUST VALVE TOWARD CLOSED POSITION DURING INSPIRATION BY THE PATIENT AND INCLUDING A FLUID PRESSURE CONTROL LINE HAVING A POINT OF CONNECTION WITH THE CONDUIT MEANS BETWEEN THE MAIN VALVE AND THE EXHAUST PORT, A CHECK VALVE IN THE CONDUIT MEANS BETWEEN SAID CONNECTION POINT AND TO EXHAUST PORT, SAID CHECK VALVE BEING ORIENTED TO PERMIT AIR FLOW IN THE DIRECTION FROM THE FAN TOWARD THE PATIENT''S DELIVERY DEVICE AND TO PREVENT AIR FLOW IN THE OPPOSITE DIRECTION, CONTROL MECHANISM FOR THE MAIN CONTROL VALVE INCLUDING A FIRST DIAPHRAGM MOVEABLE TO A CONTROL POSITION IN RESPONSE TO A BUILD-UP OF PRESSURE IN THE CONDUIT MEANS BE TWEEN THE CHECK VALVE AND THE PATIENT''S DELIVERY DEVICE A SECOND DIAPHRAGM MOVABLE TO A CONTROL POSITION IN RESPONSE TO A BUILD-UP OF PRESSURE IN THE CONDUIT MEANS BETWEEN THE CHECK VALVE AND THE PATIENT''S DELIVERY DEVICE TO CLOSE THE MAIN VALVE, A PNEUMATIC CONNECTION BETWEEN SAID DIAPHRAGMS AND THE CONDUIT MEANS, MEANS INTERCONNECTING SAID DIAPHRAGMS AND SAID MAIN CONTROL VALVE FOR OPENING THE MAIN VALVE WHEN THE FIRST DIAPHRAGM MOVES TO ITS CONTROL POSITION AND FOR CLOSING THE MAIN VALVE WHEN THE SECOND DIAPHRAGM MOVES TO ITS CONTROL POSITION, A PORT FOR VENTING THE FLUID PRESSURE CONTROL LINE; AND MEANS ASSOCIATED WITH THE MAIN VALVE TO OPEN THE PORT UPON CLOSURE OF THE MAIN VALVE AND TO CLOSE THE PORT UPON OPENING OF THE MAIN VALVE. 